Tubular suspension lamp



Feb. 7, 1939. w. E. ANDERSON 2,145,912

TUBULAR SUSPENS ION LAMP Filed March 25, 1937 5 Ezg-j INVENTOR A/VDHFJOA WWW ATTORN EY Patented 7, 1939 SUSPENSION LAMP .Waldemar 1:. Anderson, to Westinghouse El 'Mont'elair, N. 1., assignmectric & Manufacturing Company, East Pittsburgh, Pat, a corporation of Pennsylvania Applicationi Mar-ch 25,

4 Claims.

My present invention relates to incandescent lamps and particularly to that known to the art as tubular lamps.

In lamps of the tubular type it'is customary for the filament to. extend longitudinally of the elongated envelope substantially the entire length thereof. 'Since the filament becomes incandescent to give illumination upon the passage of an electric .current therethrough and when heated is subject tolincar expansion and contraction, it

has been the practice heretofore to provide a loop spring at one end of the filament which serves to connect one end of the filament to one of the leading-in. conductors and at the same time allow for expansion and contraction ofthe filament.

However, the longitudinally extending filament is usually supported intermediate its ends by pigtailsupports'which, while looping around the filament so as to supportthe same by being in actual contact therewith, allowlongitudinal expansion and contraction which might 'bessaid tobe'toward one end of the lamp, inasmuch-as the end of the filament opposite to the loop spring is rigidly secured to the remaining leading-in conductor. 25 Lamps of this type heretofore known to the art have proven very unsatisfactory in that they give I very erratic life performance. Experimental tests have indicated that filament failure, after comv paratively short life,,is attributable to'the manner in which the filament is supported. In the first place, since the customary pigtail supports are in actual contact with the or vibration to which the lamp is subjected is directly transmitted to the filament at the several points of contact whether rupted in most instances at one or more of these points after a comparativelyshort period of use.

It is accordingly an. object of my present invention to provide a lamp wherein the filament is flexibly supported in its entiretyso that abrasion of the filament is prevented upon expansion and 55 type which are I filament, any shock I such shock be caused I by mechanical vibration exteriorly of the lamp or contraction thereof during operation of said lamp.

1937, Serial No. 132,985 (oi. 176-39) Another object of my invention is the provision of an incandescent lamp wherein the filament is cradled within the envelope in such a way that accidental shocks are prevented from being transmitted to the filament and mechanical abrasion thereof during expansion and contraction is precluded.

A further object of my present invention is the provision of an incandescent lamp of the tubular type wherein the filament extends longitudinally of the envelope and is supported by spaced springlike supports which so cradle the filament as to preclude external shocks being transmitted to the filament and mechanical abrasion thereof is prevented due to expansion and contraction during operation.

Still further objects of my present invention will become obvious to those skilled in the art by reference to the accompanying drawing where:

Fig. 1 is a plan view of a lamp constructed in accordance with my present invention,

Fig. 2 is a sectional view on an enlarged scale with parts thereof broken away, of a lamp constructed in accordance with my present invention andshowing the contracted position of the filament after extinguishment of the lamp.

Fig. 3 is a sectional view in all respects similar to Fig. 2 with the exception that the filament is shown in its expanded position during operation of the lamp and incandescence of the filament,

Fig. 4 is a sectional view taken on the line -IV-IV of Fig. 1 and looking in the direction indicated by the arrows.

shown in Fig. 1 an elongated vitreous evacuated envelope 5 provided with the usual threaded base 6 for connection to a socket carrying electricalform an integral conductor which extends substantially the entire length of the envelope.

In order to rigidly maintain the leading-in conductor 9 in a fixed position relative to the longitudinalaxis of the envelope and parallel therewith, I provide a plurality of metallic yoke members l2. By reference more particularly to Fig. 4

- it will be noted that these yoke members are of substantially M-shaped configuration and due to Referring now to the drawing in detail, I have the resilience thereof are maintained in contact with the wall of the envelope at four points about its periphery. Inasmuch as these yokes loop around the leading-in conductor and are thus in firm engagement therewith, the conductor is rigidly maintained in a fixed position within the envelope and eccentric to the longitudinal axis of the same.

Also positioned within the envelope and in close proximity to the longitudinal axis thereof, is a filament l3, which may be of suitable metal such as tungsten or the like, that becomes incandescent when supplied with electrical energy.

In order to prevent external shock to the filament from any cause such as by accidental Jarring of the lamp and also by mechanical vibration due to the influence of alternatingcurrent, I support the filament by what may be termed a cradle or floating construction. One end of the filament I3 is supported by a spring-like flexible member M which is rigidly connected to the filament and to the leading-in conductor 8 in any suitable manner, such as by welding or the like. Similarly the opposite end of the filament I3 is connected to the extremity of the longitudinally extending leading-in conductor portion ID to thus flexibly suspend the filament.

These spring-like members l4 may be formed of any suitable metal which will retain its resilience when subjected to high temperatures and they serve not only as a flexible support but also for conducting electrical energy from the leading-in conductorsto the filament. Due to the cradle-like or freely floating suspension of the filament l3 any shock to the lamp irrespective of its cause is accordingly absorbed by the flexible spring-like supports so that it is not transmitted to the filament.

Although it is possible to support the filament solely at its ends, such would necessitate placing the end supports under considerable tension which would thus tend to stretch the filament. Accordingly, to prevent this with attendant sagging and contacting of the walls of the envelope, it is preferable to interpose a plurality of additional spaced spring-like members M which are also rigidly connected to both the filament and the leading-in conductor 9. However, since these members I4 are of metal and consequently electrically conductive, I insulate the same from the leading-in conductor 9, although making a rigid connection therebetween, to prevent shortcircuiting of any portion of the filament Ill. Accordingly, any suitable insulating joint may be formed, although I find it preferable to utilize a glass bead l5 fused to the leading-in conductor 9 at desired points along its length and having one end of the spring-like members [4 embedded therein while the opposite ends of the members M are secured to the filament l3 by welding or the like as previously mentioned.

Thus the filament intermediate its ends is also cradled by being flexibly supported, which not only prevents sagging and contacting with the walls of the envelope but such flexible mem-. bers all cooperate in absorbing any shocks or jarring so that the useful life of the filament is not impaired. In addition to absorbing shock, my cradle or floating suspension of the filament I3 has the further advantage of permitting expansion and contraction thereof which inherently occurs with changes of temperature.

By referencemore particularly to Fig. 2 it will be noted that the filament i3 is in its contracted position since the lamp is extinguished as: indicated by the open position of a switch l6 which disconnects the lamp from the source of commercial supply represented by the conductors Li' and L2. In the contracted position of the filament iii the spring-like members l4 disposed at the ends of the filament are of slightly arcuate form and are constantly under tension in opposition to each other. As to the intermediate spring members H the only tension to which they are subjected is that of the weight of the filament but they are angularly disposed toward one another so as to be yieldable in an opposite direction upon expansion of the filament. I

Referring now to Fig. 3 since the switch it is closed, the filament l3 will receive electrical energyfrom the source L1, L2 and consequently becomes incandescent. This causes the temperature of the tungsten filament to rise very high with inherent. expansion thereof. Upon expansion the spring-like members I 4 at the ends of the filament flex in a direction away from each other and toward the ends of the lamp from the position shown in dotted lines to that specifically shown in Fig. 3. At the same time the intermediate spring-like members move in opposite directions similar to the end members as also shown in this figure. It should also be noted that the linear expansion of the filament is substantially equal in opposite directions from the center so that the intermediate spring-like members I 4 are flexed approximately one-half as much as the end members ll, or in other words, the ends of the intermediate members l4 which are connected to the filament, move in the direction of the longitudinal axis of the lamp about one-half the distance of travel of the end members It;

It thus becomes obvious to those skilled in the art that I have provided a lamp wherein the filament is entirely supported by a cradle-like or freely floating arrangement comprising a plurality of spring-like members rigidly secured to the leading-in conductors and to the filament. Owing to such construction, shocks to the lamp are precluded from being transmitted to the filament and are absorbed by the floating cradle or spring-like supports. Moreover, since all the spring-like supporting members are rigidly connected to the filament, expansion and contraction thereof in no way causes any mechanical abrasion which, together with shocks and vibrations, would otherwise materially shorten the useful life of the lamp.

Although I have shown and described one specific embodiment of my invention, I do not de-,

sire to be limited thereto as various other modifications may be made without departing from the spirit and scope of the appended claims.

What is claimed is:

1. An electric incandescent lamp comprising a vitreous envelope, a filament in said envelope, a pair of leading-in conductors extending an appreciable distance within said envelope, and a plurality of auxiliary flexible support members rigidly secured to said leading-in conductors and rigidly secured to said filament to allow contraction and expansion of said filament without abrasion thereof.

2. An electric incandescent lamp comprising an elongated vitreous envelope, a filament extending substantially the entire length of said envelope, a longitudinally extending member rigidly positioned within said envelope for supporting said filament, and a plurality of flexible members having ends thereof rigidly secured to said longitudinally extending member and the other ends 7 thereof rigidly secured to said filament to prevent abrasion or said filament throughout its length upon linear expansion and contraction thereof.

3. An electric incandescent lamp comprising a vitreous envelope provided with a press, leadingin conductors extending through said press and interiorly' of said envelope, and a plurality of yieldable members having ends thereof rigidly secured to said leading-in conductors and the other ends thereoi rigidly secured to said filament to allow movement of said filament relative to said leading-in conductors during contraction and expansion thereof and to prevent movement between said filament and said yieldable members to eliminate abrasion of said filament.

4. An electric incandescent lamp comprising an elongated vitreous envelope provided with a press, leading-in conductors extending through said press interiorly of said envelope and at least one oi said leading-in conductors extending substantially the entire length of said enve1ope,'a filament disposed substantially parallel to the longitudinally extending leading-in conductor, a

plurality of spaced supports ensuing the longitudinally extending leading-in conductor and contacting the wall oi said envelope ior rigidly maintaining the longitudinally extending leadingin conductor in a fixed position relative to said envelope, a yieldable member at each end of said filament having one end thereof rigidly connected to the respective leading-in conductors and the other end thereof rigidly connected to said filament, and at least one yieldable member disposed intermediate said first mentioned yieldable members having one end thereot rigidly connected to said filament and the other end thereof rigidly secured to said longitudinally extending leadingin conductor, and cooperating with said first mentioned yieldable members to allow movement of said filament relative to said leading-in conductors and to prevent movement between said filament and said yieldable members to eliminate abrasion of said filament.

WALDEMAR E. ANDERSON. 

